Carboxymethyl‐β‐cyclodextrin influence on the solubility and toxicity of substituted indole compounds

The solubilization of eight selected substituted indole compounds (SICs) by carboxymethyl‐β‐cyclodextrin (CMCD) in water is reported. The results show that their solubility was well improved in CMCD aqueous solution, and the stoichiometry of inclusion complex of the studied SICs with CMCD was 1: 1. The acute toxicity to Photobacterium phosphoreum of the investigated SICs in CMCD aqueous solutions was also investigated and was compared with that in water. The results show that the toxicity of five studied SICs decreased while the toxicity of the rest three SICs increased in CMCD aqueous solutions, but neither the increase nor the decrease was significant.     

Voltammetric study on the interaction of the heavy metals Cd(II) and Mn(II) with transfer‐RNA,DNA and other polynucleotides

Small amounts of bivalent cations, usually provided by Mg²⁺, are in the living cell necessary for the biological activity of t‐RNA as these bivalent cations influence the tertiary and secondary structure of this globular polynucleotide.

In context with the discussed possibility of carcinogenic actions of ingested Cd it is of particular interest to check whether there exist specific strong interactions of this toxic heavy metal with nucleic acids.

Therefore, the binding of the toxic heavy metal ion Cd²⁺ and the essential heavy metal ion Mn²⁺ to t‐RNA and for comparison to DNA and the polynucleotides poly‐U, poly‐A and poly‐A‐poly‐U has been studied. Free metal ion concentrations have been determined by differential pulse polararography. Association constants and the number of binding sites have been evaluated by the Scatchard method and alternatively according to a simple electrostatic model of the polyelectrolytes. With the Scatchard method for t‐RNA and all polynucleotides with helical structure two different binding sites of different strength are observed. Those with higher association constants are assigned to the helical parts of t‐RNA. Interaction sites with low association constants correspond to the parts with no ordered tertiary structure, as their exclusive occurrence for poly‐U, having a completely stochastic coil structure, reflects. The values of the association constants for the stronger and weaker association sites are in the respective polynucleotides for both investigated bivalent metal ions of comparable magnitude. This emphasizes that the interaction is essentially of electrostatic nature and depends primarily on the charge of the interacting species.

Thus the specific strong interaction of Cd by the intercalation into the tertiary structure of nucleic acids or by chelation of their base units can be ruled out as one possibility for carcinogenity of Cd.

Moreover, under physiological conditions the high excess of competitive Mg²⁺ will suppress the interaction of Cd based on electrostatic forces.     

Study of the levels of N‐methylcarbamate pesticides in waters of the river Huelva

A study on the levels of N‐methylcarbamate pesticides and some degradation products in waters of the river Huelva was carried out. This river constitutes the main water supply of the city of Seville at the south west of Spain with a population of almost one million inhabitants. N‐methylcarbamates were extracted from the water by using C‐18 solid phase cartridges. High performance liquid chromatography with UV detection was used to carry out the determinations. Residues of carbaryl, methiocarb sulphoxide and α‐naphthol were found in some of the analysed water samples.     

Transport of metanil yellow in the rat plasma and interaction of its metabolite,p‐aminodiphenylamine with serum proteins

Binding affinity of metanil yellow and its breakdown product p‐aminodiphenylamine to serum proteins has been studied employing chromatographic separation on Sephadex G‐200 and by paper and polyacrylamide gel electrophoresis. Metanil yellow has more affinity towards albumin than to globulins. The complexing is presumably through electrostatic forces. p‐Aminodiphenylamine on the other hand, preferably binds to globulin fractions of serum protein. However, a stable binding with BSA alone was also observed. The binding was quite stable and was accompanied by a shift in absorbance from 430 nm to 500 nm. Aspartic acid moiety of protein was found to be one of the units involved in the binding of p‐ADPA to proteins.     

Cross‐sectional epidemiological study on the lead burden of children and workers in Greece

Exposure of the general population to lead in the environment is mainly caused by motor traffic exhaust and by industrial pollution. The aim of the study in Greece was to assess lead exposure in children living in point source impacted areas (Lavrion and Aspropyrgos‐Eleusis) using the biological monitoring parameter “blood lead concentration”;.

In addition, workers of a lead smelter, a battery plant and an oil refinery were investigated in these areas at the same time.

Five hundred and thirty‐four children and 105 workers took part in this investigation.

The highest blood lead levels (mean: 24.16 μg/100ml; range: 10.40–60.49 μg/100 ml) were found in children living in a 500m‐area around the lead smelter at Lavrion. Blood lead decreases corresponded to the increasing distance from the emitter. Nevertheless the values of children living in a 1500 m distance to the smelter are significantly higher than those of children living next to other kinds of industrial lead sources.

The mean values of the children living in the two industrial towns were manifold higher than those of the control group.

The blood lead levels of the investigated workers did not exceed the German BAT‐value (Biologischer Arbeitsstoff‐Toleranzwert) of 70 μg/100ml.     

Anaerobic degradation of 4‐chlorophenol under denitrifying conditions with nitrate as the only electron acceptor

A denitrifying bacterium was isolated from activated sludge after enrichment on 4‐chlorophenol under anoxic, denitrifying conditions, and the microbial degradation of 4‐chlorophenol by this bacterium, with nitrate as the only electron acceptor, was investigated. The bacterium was capable of degrading up to 5 mM 4‐chlorophenol with stoichiometric release of chloride under denitrifying conditions. Anaerobic degradation of 4‐chlorophenol was dependent on nitrate as an electron acceptor. Nitrate (10 mM) severely inhibited the growth by the toxic effect of the accumulated nitrite. The optimum nitrate concentration for cell growth and chlorophenol degradation was 6 mM.     

End-users’ knowledge,attitude, and behavior towards safe use of pesticides: a case study in the Guanting Reservoir area,China

Pesticides are widely used in China for crop protection. However, the use of some highly toxic and accumulative pesticides has led to serious pollution to the environment. The knowledge that end-users of pesticides have about hazards is important for the prevention of acute poisoning. Moreover, farmers, especially those who purchase and use pesticides, often make important and long-standing impacts on the local ecosystem and environment. In this study, a specially designed questionnaire was used to collect information on their knowledge, attitude, and behavior related to pesticides in the Guanting Reservoir area, north of China. Most pesticide end-users reported that they took incomplete preventive measures for lack of extensive pesticide knowledge and information. Pesticide information, instruction, and training among farmers should be promoted, and governmental intervention is needed to ensure proper management regarding public health risks and environmental hazards.